Organic electroluminescence device and organic light emitting medium

ABSTRACT

An organic electroluminescence device having a layer of an organic light emitting medium which comprises (A) a specific arylamine compound and (B) at least one compound selected from specific anthracene derivatives, spirofluorene derivatives, compounds having condensed rings and metal complex compounds and is disposed between a pair of electrodes and an organic light emitting medium comprising the above components (A) and (B) are provided. The organic electroluminescence device exhibits a high purity of color, has excellent heat resistance and a long life and efficiently emits bluish to yellowish light. The organic light emitting medium can be advantageously used for the organic electroluminescence device.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/675,037, filed Nov. 13, 2012, now pending; which is a division ofapplication Ser. No. 12/773,307, filed May 4, 2010, now U.S. Pat. No.8,334,648; which is a continuation of application Ser. No. 11/207,933,filed Aug. 22, 2005, now U.S. Pat. No. 7,927,716, which is a division ofapplication Ser. No. 10/617,397, filed Jul. 11, 2003, now U.S. Pat. No.7,651,786. Priority to Japan 2002-211308, filed Jul. 19, 2002, isclaimed, and all are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an organic electroluminescence(“electroluminescence” will be referred to as “EL”, hereinafter) deviceand an organic light emitting medium, and more particularly, to anorganic EL device which exhibits excellent purity of color, hasexcellent heat resistance and a long life and efficiently emits bluishto yellowish light and an organic light emitting medium which isadvantageously used for the organic EL device.

BACKGROUND ART

An organic EL is a spontaneous light emitting device which utilizes theprinciple that a fluorescent substance emits light by energy ofrecombination of holes injected from an anode and electrons injectedfrom a cathode when an electric field is applied.

Since an organic EL device of the laminate type driven under a lowelectric voltage was reported by C. W. Tang of Eastman Kodak Company (C.W. Tang and S. A. Vanslyke, Applied Physics Letters, Volume 51, Pages913, 1987), many studies have been conducted on organic EL devices usingorganic materials as the constituting materials.

Tang et al used a laminate structure usingtris(8-hydroxy-quinolinato)aluminum for the light emitting layer and atriphenyldiamine derivative for the hole transporting layer. Advantagesof the laminate structure are that the efficiency of hole injection intothe light emitting layer can be increased, that the efficiency offorming excited particles which are formed by blocking and recombiningelectrons injected from the cathode can be increased and that excitedparticles formed within the light emitting layer can be enclosed. As thestructure of the organic EL device, a two-layered structure having ahole transporting (injecting) layer and an electron transporting andlight emitting layer and a three-layered structure having a holetransporting (injecting) layer, a light emitting layer and an electrontransporting (injecting) layer are well known. To increase theefficiency of recombination of injected holes and electrons in thedevices of the laminate type, the structure of the device and theprocess for forming the device have been studied.

As the light emitting material, chelate complexes such astris(8-quinolinato)aluminum, coumarine derivatives,tetraphenyl-butadiene derivatives, bisstyrylarylene derivatives andoxadiazole derivatives are known. It is reported that light in thevisible region ranging from blue light to red light can be obtained byusing these light emitting materials and development of a deviceexhibiting color images is expected (For example, Japanese PatentApplication Laid-Open Nos. Heisei 8 (1996)-239655, Heisei 7(1995)-138561 and Heisei 3 (1991)-200289).

Devices using bisanthracene derivatives as the hole transportingmaterial or the light emitting material are disclosed in the U.S. Pat.No. 3,008,897 and Japanese Patent Application Laid-Open No. Heisei 8(1996)-12600. Although bisanthracene derivatives can be used as thematerial emitting blue light, the efficiency of light emission and thelife are insufficient for practical applications. In Japanese PatentApplication Laid-Open No. 2001-207167, a device using an aminoanthracenederivative as the material emitting green light is disclosed. However,the organic EL device using this material cannot be used for thepractical applications since the device has poor heat resistance due tothe low glass transition temperature of the material and light emissionof a long life and a high efficiency cannot be obtained. Other organicdevices of a long life and excellent properties are recently reported.However, the life and the properties are not always sufficient.Therefore, the development of an organic EL device exhibiting moreexcellent properties have been strongly desired.

DISCLOSURE OF THE INVENTION

Under the above circumstances, the present invention has an object ofproviding an organic EL device which exhibits a high purity of color,has excellent heat resistance and a long life and efficiently emitsbluish to yellowish light and an organic light emitting medium which canbe advantageously used for the organic EL device.

As the result of extensive studies by the present inventors to achievethe above object, it was found that, when an organic light emittingmedium comprised a combination of a specific arylamine compound and atleast one compound selected from specific anthracene derivatives,spirofluorene derivatives, compounds having condensed rings and metalcomplex compounds and an organic electroluminescence device had a layerof the medium disposed between a pair of electrodes, the organic ELdevice exhibited a high purity of color, had excellent heat resistanceand a long life and efficiently emitted bluish to yellowish light. Thepresent invention has been completed based on this knowledge.

The present invention provides an electroluminescence device comprisinga pair of electrodes and a layer of an organic light emitting mediumdisposed between the pair of electrodes, wherein the layer of an organiclight emitting medium comprises:

(A) at least one compound selected from substituted and unsubstitutedarylamines having 10 to 100 carbon atoms, and

(B) at least one compound selected from:

-   -   anthracene derivatives represented by following general formula        (I)

A¹-L-A²  (I)

wherein A¹ and A² each independently represent a substituted orunsubstituted monophenylanthryl group or a substituted or unsubstituteddiphenylanthryl group and may represent a same group or differentgroups, and L represents a single bond or a divalent bonding group,

-   -   anthracene derivatives represented by following general formula        (II):

A³-An-A⁴  (II)

wherein An represents a substituted or unsubstituted divalent anthraceneresidue group, A³ and A⁴ each independently represent a substituted orunsubstituted aryl group having 6 to 40 carbon atoms, at least one of A³and A⁴ represents a substituted or unsubstituted monovalent condensedaromatic ring group or a substituted or unsubstituted aryl group having10 or more carbon atoms, and A³ and A⁴ may represent a same group ordifferent groups,

-   -   spirofluorene derivatives represented by following general        formula (III):

wherein Ar¹ represents a substituted or unsubstituted spirofluoreneresidue group, A⁵ to A⁸ each independently represent a substituted orunsubstituted aryl group having 6 to 40 carbon atoms,

-   -   compounds having condensed rings represented by following        general formula (IV):

wherein Ar² represents a substituted or unsubstituted aromatic ringgroup having 6 to 40 carbon atoms, A⁹ to A¹¹ each independentlyrepresent a substituted or unsubstituted arylene group having 6 to 40carbon atoms, A¹² to A¹⁴ each independently represent hydrogen atom, analkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, an aryloxylgroup having 5 to 18 carbon atoms, an aralkyloxyl group having 7 to 18carbon atoms, an arylamino group having 5 to 16 carbon atoms, nitrogroup, cyano group, an ester group having 1 to 6 carbon atoms or ahalogen atom, and at least one of A⁹ to A¹⁴ represents a group havingcondensed aromatic rings, and

-   -   metal complex compounds. The present invention also provides an        electroluminescence device described above, wherein        component (B) is at least one compound selected from the        anthracene derivatives represented by general formulae (I)        and (II) shown above.

The present invention provides an organic light emitting medium whichcomprises (A) at least one compound selected from substituted andunsubstituted arylamines having 10 to 100 carbon atoms and (B) at leastone compound selected from anthracene derivatives represented by generalformula (I) shown above, anthracene derivatives represented by followinggeneral formula (II) shown above, spirofluorene derivatives representedby general formula (III) shown above, compounds having condensed ringsrepresented by general formula (IV) shown above and metal complexcompounds described above. The present invention also provides anorganic light emitting medium described above, wherein component (B) isat least one compound selected from the anthracene derivativesrepresented by general formulae (I) and (II) shown above.

THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION

The organic EL device of the present invention is a device having astructure comprising a pair of electrodes and a layer of an organiclight emitting medium disposed between the pair of electrodes.

In the present invention, an organic light emitting medium comprising acombination of (A) at least one compound selected from substituted andunsubstituted arylamine compounds having 10 to 100 carbon atoms and (B)at least one compound selected from the anthracene derivativesrepresented by the above general formula (I), the anthracene derivativesrepresented by the above general formula (II), the spirofluorenederivatives represented by the above general formula (III), thecompounds having condensed rings represented by the above generalformula (IV) and the above metal complex compounds, is used in the layerof an organic light emitting medium.

Examples of the arylamine compound of component (A) include arylaminecompounds represented by the following general formula (V):

wherein X³ represents a substituted or unsubstituted condensed aromaticring group having 10 to 40 nuclear carbon atoms, Ar⁵ and Ar⁶ eachindependently represent a substituted or unsubstituted monovalentaromatic group having 6 to 40 carbon atoms, and p represents an integerof 1 to 4.

In general formula (V), examples of the group represented by X³ includeresidue groups derived from naphthalene, phenanthrene, fluoranthene,anthracene, pyrene, perylene, coronene, chrysene, picene,diphenylanthracene, fluorene, triphenylene, rubicene, benzoanthracene,phenylanthracene, bisanthracene, dianthracenylbenzene anddibenzoanthracene. Among these groups, residue groups derived fromchrysene, pyrene and anthracene are preferable.

Examples of the monovalent aromatic group having 6 to 40 carbon atomswhich is represented by Ar⁵ and Ar⁶ include phenyl group, naphthylgroup, anthranyl group, phenanthryl group, pyrenyl group, coronyl group,biphenyl group, terphenyl group, fluorenyl group, furanyl group, thienylgroup, benzothienyl group, indolyl group and carbazolyl group. Amongthese groups, phenyl group, naphthyl group, pyrenyl group and biphenylgroup are preferable.

As the arylamine compound represented by general formula (V), arylaminecompounds represented by the following general formula (V-a):

wherein X³ is as defined in general formula (V), are preferable.

In the above general formula (V-a), Ar¹⁵ to Ar¹⁸ each independentlyrepresent hydrogen atom, a substituted or unsubstituted alkyl grouphaving 1 to 50 carbon atoms and preferably 1 to 20 carbon atoms, asubstituted or unsubstituted aryl group having 5 to 50 carbon atoms andpreferably 5 to 20 carbon atoms, a substituted or unsubstituted aralkylgroup having 7 to 50 carbon atoms and preferably 7 to 40 carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 50 carbonatoms and preferably 5 to 12 carbon atoms, a substituted orunsubstituted alkoxyl group having 1 to 50 carbon atoms and preferably 1to 6 carbon atoms, a substituted or unsubstituted aryloxyl group having5 to 50 carbon atoms and preferably 5 to 18 carbon atoms, a substitutedor unsubstituted arylamino group having 5 to 50 carbon atoms andpreferably 5 to 18 carbon atoms or a substituted or unsubstitutedalkylamino group having 1 to 20 carbon atoms and preferably 1 to 6carbon atoms.

Examples of the substituted or unsubstituted alkyl group represented byAr¹⁵ to Ar¹⁸ include methyl group, ethyl group, propyl group, isopropylgroup, butyl group, sec-butyl group, tert-butyl group, pentyl group,hexyl group, heptyl group, octyl group, stearyl group, 2-phenylisopropylgroup, trichloromethyl group, trifluoromethyl group, benzyl group,α-phenoxybenzyl group, α,α-dimethylbenzyl group, α, α-methylphenylbenzylgroup, α, α-ditrifluoromethylbenzyl group, triphenylmethyl group andα-benzyloxybenzyl group.

Examples of the substituted or unsubstituted aryl group represented byAr¹⁵ to Ar¹⁸ include phenyl group, 2-methylphenyl group, 3-methylphenylgroup, 4-methylphenyl group, 4-ethylphenyl group, biphenyl group,4-methylbiphenyl group, 4-ethylbiphenyl group, 4-cyclohexylbiphenylgroup, terphenyl group, 3,5-dichlorophenyl group, naphthyl group,5-methylnaphthyl group, anthryl group and pyrenyl group.

Examples of the substituted or unsubstituted aralkyl group representedby Ar¹⁵ to Ar¹⁸ include benzyl group, 1-phenylethyl group, 2-phenylethylgroup, 1-phenylisopropyl group, 2-phenylisopropyl group, phenyl-t-butylgroup, α-naphthylmethyl group, 1-α-naphthylethyl group,2-α-naphthylethyl group, 1-α-naphthylisopropyl group,2-α-naphthylisopropyl group, β-naphthylmethyl group, 1-β-naphthylethylgroup, 2-β-naphthylethyl group, 1-β-naphthylisopropyl group,2-β-naphthylisopropyl group, 1-pyrrolylmethyl group, 2-(1-pyrrolyl)ethylgroup, p-methylbenzyl group, m-methylbenzyl group, o-methylbenzyl group,p-chlorobenzyl group, m-chlorobenzyl group, o-chlorobenzyl group,p-bromobenzyl group, m-bromobenzyl group, o-bromobenzyl group,p-iodobenzyl group, m-iodobenzyl group, o-iodobenzyl group,p-hydroxybenzyl group, m-hydroxybenzyl group, o-hydroxybenzyl group,p-aminobenzyl group, m-aminobenzyl group, o-aminobenzyl group,p-nitrobenzyl group, m-nitrobenzyl group, o-nitrobenzyl group,p-cyanobenzyl group, m-cyanobenzyl group, o-cyanobenzyl group,1-hydroxy-2-phenylisopropyl group and 1-chloro-2-phenylisopropyl group.

Examples of the substituted or unsubstituted cycloalkyl grouprepresented by Ar¹⁵ to Ar¹⁸ include cyclopropyl group, cyclobutyl group,cyclopentyl group and cyclohexyl group.

Examples of the substituted or unsubstituted alkoxyl group representedby Ar¹⁵ to Ar¹⁸ include methoxyl group, ethoxyl group, propoxyl group,isopropoxyl group, butoxyl group, isobutoxyl group, sec-butoxyl group,tert-butoxyl group, various types of pentyloxyl groups and various typesof hexyloxyl groups.

Examples of the substituted or unsubstituted aryloxyl group representedby Ar¹⁵ to Ar¹⁸ include phenoxyl group, tolyloxyl group and naphthyloxylgroup.

Examples of the substituted or unsubstituted arylamino group representedby Ar¹⁵ to Ar¹⁸ include diphenylamino group, ditolylamino group,dinaphthylamino group and naphthylphenylamino group.

Examples of the substituted or unsubstituted alkylamino grouprepresented by Ar¹⁵ to Ar¹⁸ include dimethylamino group, diethylaminogroup and dihexylamino group.

In general formula (V-a), g, h, i and j each represent an integer of 0to 5 and preferably an integer of 0 to 2. Atoms and groups representedby a plurality of Ar¹⁵ to Ar¹⁸ may be the same with or different fromeach other and may be bonded to each other to form a saturated orunsaturated ring when g, h, i and j each represent an integer of 2 orgreater. n represents an integer of 0 to 3. At least one of Ar¹⁵ to Ar¹⁸represents a substituted or unsubstituted secondary or tertiary alkylgroup having 3 to 10 carbon atoms. Examples of the secondary or tertiaryalkyl group include the secondary and tertiary alkyl groups among thegroups described as the examples of the alkyl group represented by Ar¹⁵to Ar¹⁸.

As the arylamine compound represented by general formula (V), arylaminecompounds represented by the following general formula (V-b):

wherein X³, Ar¹⁵ to Ar¹⁸, g, h, i and j are as defined in generalformula (V-a), and atoms and groups represented by a plurality of Ar¹⁵to Ar¹⁸ may be the same with or different from each other and may bebonded to each other to form a saturated or unsaturated ring when g, h,i and j each represent an integer of 2 or greater, are also preferable.

In general formula (V-b), R²⁴ and R²⁵ each independently representhydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10carbon atoms and preferably 1 to 6 carbon atoms, a substituted orunsubstituted aryl group having 6 to 20 carbon atoms and preferably 6 to14 carbon atoms, a substituted or unsubstituted aralkyl group having 7to 50 carbon atoms and preferably 7 to 40 carbon atoms, a substituted orunsubstituted alkoxyl group having 1 to 50 carbon atoms and preferably 1to 6 carbon atoms or a substituted or unsubstituted aryloxyl grouphaving 5 to 50 carbon atoms and preferably 5 to 18 carbon atoms.

Examples of the groups represented by R²⁴ and R²⁵ include the groups inwhich the number of carbon atoms is within the above range among thegroups described as the examples of the groups represented by Ar¹⁵ toAr¹⁸.

At least one of R²⁴ and R²⁵ represents a substituted or unsubstitutedsecondary or tertiary alkyl group having 3 to 10 carbon atoms. Examplesof the secondary or tertiary alkyl group include the secondary andtertiary alkyl groups among the groups described as the examples of thealkyl group represented by Ar¹⁵ to Ar¹⁸.

In general formula (V-b), k and m each represent an integer of 0 to 2.

In the present invention, the arylamine compound of component (A) may beused singly or in combination of two or more.

Examples of the substituent in the compounds represented by generalformulae (V), (V-a) and (V-b) include alkyl groups having 1 to 6 carbonatoms, cycloalkyl groups having 3 to 6 carbon atoms, alkoxyl groupshaving 1 to 6 carbon atoms, aryloxyl groups having 5 to 18 carbon atoms,aralkyloxyl groups having 7 to 18 carbon atoms, arylamino groups having5 to 16 carbon atoms, nitro group, cyano group, ester groups having 1 to6 carbon atoms and halogen atoms. Examples of the above groups and atomsinclude the atoms and groups described as the examples of the atoms andthe groups represented by A¹² to A¹⁴ in general formula (IV) describedin the following.

In the present invention, the compound of component (B) is at least onecompound selected from [1] anthracene derivatives represented by thefollowing general formula (I), [2] anthracene derivatives represented bythe following general formula (II), [3] spirofluorene derivativesrepresented by the following general formula (III), [4] compounds havingcondensed rings represented by the following general formula (IV) and[5] metal complex compounds shown in the following.

It is preferable that the compound of component (B) is at least onecompound selected from the anthracene derivatives represented by generalformulae (I) and (II).

[1] Anthracene derivatives represented by general formula (I):

A¹-L-A²  (I)

wherein A¹ and A² each independently represent a substituted orunsubstituted monophenylanthryl group or a substituted or unsubstituteddiphenylanthryl group and may represent the same group or differentgroups, and L represents a single bond or a divalent bonding group.

As the anthracene derivative represented by general formula (I),anthracene derivatives represented by the following general formula(I-a) and anthracene derivatives represented by the following generalformula (I-b) are preferable.

In the above general formula (I-a), R¹ to R¹⁰ each independentlyrepresent hydrogen atom, an alkyl group, a cycloalkyl group, an arylgroup which may be substituted, an alkoxyl group, an aryloxyl group, analkylamino group, an alkenyl group, an arylamino group or a heterocyclicgroup which may be substituted, a and b each represent an integer of 1to 5, atoms or groups represented by a plurality of R¹ and R² may be thesame with or different from each other and may be bonded to each otherto form a ring when a and b each represent an integer of 2 or greater,groups represented by combinations of R³ and R⁴, R⁵ and R⁶, R⁷ and R⁸,and R⁹ and R¹⁰ may be bonded to each other to form a ring, and L¹represents a single bond, —O—, —S—, —N(R)— (R representing an alkylgroup or an aryl group which may be substituted), an alkylene group oran arylene group.

In the above general formula (I-b), R¹¹ to R²⁰ each independentlyrepresent hydrogen atom, an alkyl group, a cycloalkyl group, an arylgroup which may be substituted, an alkoxyl group, an aryloxyl group, analkylamino group, an arylamino group or a heterocyclic group which maybe substituted, c, d, e and f each represent an integer of 1 to 5, atomsor groups represented by a plurality of R¹¹, R¹² ₅ R¹⁶ and R¹⁷ may bethe same with or different from each other and may be bonded to eachother to form a ring when c, d, e and f each represent an integer of 2or greater, groups represented by combinations of R¹³ and R¹⁴, and R¹⁸and R¹⁹ may be bonded to each other to form a ring, and L² represents asingle bond, —O—, —S—, —N(R)— (R representing an alkyl group or an arylgroup which may be substituted), an alkylene group or an arylene group.

That a group may be substituted means the group is substituted orunsubstituted.

In the above general formulae (I-a) and (I-b), among the groupsrepresented by R¹ to R²⁰, alkyl groups having 1 to 6 carbon atoms,cycloalkyl groups having 3 to 6 carbon atoms, aryl groups having 5 to 18carbon atoms, alkoxyl groups having 1 to 6 carbon atoms, aryloxyl groupshaving 5 to 18 carbon atoms and alkenyl groups having 1 to 6 carbonatoms are preferable; amino groups substituted with an aryl group having5 to 16 carbon atoms are preferable as the arylamino group; and triazolegroup oxadiazole group, quinoxaline group, furanyl group and thienylgroup are preferable as the heterocyclic groups.

As the alkyl group represented by R in —N(R)— which is represented by L¹and L², alkyl groups having 1 to 6 carbon atoms, alkylene groups having1 to 20 carbon atoms and aryl groups having 5 to 18 carbon atoms arepreferable.

[2] Anthracene derivatives represented by general formula (II):

A³-An-A⁴  (II)

wherein An represents a substituted or unsubstituted divalent anthraceneresidue group, A³ and A⁴ each independently represent a substituted orunsubstituted aryl group having 6 to 40 carbon atoms, at least one of A³and A⁴ represents a substituted or unsubstituted monovalent condensedaromatic ring or a substituted or unsubstituted aryl group having 10 ormore carbon atoms, and A³ and A⁴ may represent the same group ordifferent groups.

Examples of the aryl group represented by A³ and A⁴ include phenylgroup, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group,4-ethylphenyl group, biphenyl group, 4-methylbiphenyl group,4-ethylbiphenyl group, 4-cyclohexylbiphenyl group, terphenyl group,3,5-dichlorophenyl group and condensed aromatic ring groups which areresidue groups derived from naphthalene, phenanthrene, fluoranthene,anthracene, pyrene, perylene, coronene, chrysene, picene, fluorene,terphenyl, diphenylanthracene, biphenyl, carbazole, triphenylene,rubicene, benzoanthracene, phenylanthracene, bisanthracene,dianthracenylbenzene and dibenzoanthracene, which may be substituted orunsubstituted.

As the anthracene derivative represented by the above general formula(II), anthracene derivatives represented by the following generalformula (II-a):

X¹-An-X²  (II-a)

wherein An represents a substituted or unsubstituted divalent anthraceneresidue group and X¹ and X² each independently represent a monovalentresidue group derived from naphthalene, phenanthrene, fluoranthene,anthracene, pyrene, perylene, coronene, chrysene, picene,diphenylanthracene, carbazole, triphenylene, rubicene, benzoanthracene,phenylanthracene, bisanthracene, dianthracenylbenzene ordibenzoanthracene, which may be substituted or unsubstituted, arepreferable.

[3] Spirofluorene derivatives represented by general formula (III):

wherein Ar¹ represents a substituted or unsubstituted spirofluoreneresidue group, A⁵ to A⁸ each independently represent a substituted orunsubstituted aryl group having 6 to 40 carbon atoms.

Examples of the substituted or unsubstituted aryl group represented byA⁵ to A⁸ in the above general formula (III) include phenyl group,2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group,4-ethylphenyl group, biphenyl group, 4-methylbiphenyl group,4-ethylbiphenyl group, 4-cyclohexylbiphenyl group, terphenyl group,3,5-dichlorophenyl group, naphthyl group, 5-methylnaphthyl group,anthryl group and pyrenyl group.

As the spirofluorene derivative represented by the above general formula(III), spirofluorene derivatives represented by the following generalformula (III-a):

wherein A⁵ to A⁸ each independently represent a substituted orunsubstituted biphenyl group or a substituted or unsubstituted naphthylgroup, are preferable.

[4] Compounds having condensed rings represented by general formula(IV):

wherein Ar² represents a substituted or unsubstituted aromatic ringgroup having 6 to 40 carbon atoms, A⁹ to A¹¹ each independentlyrepresent a substituted or unsubstituted arylene group having 6 to 40carbon atoms, A¹² to A¹⁴ each independently represent hydrogen atom, analkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, an aryloxygroup having 5 to 18 carbon atoms, an aralkyloxyl group having 7 to 18carbon atoms, an arylamino group having 5 to 16 carbon atoms, nitrogroup, cyano group, an ester group having 1 to 6 carbon atoms or ahalogen atom, and at least one of A⁹ to A¹⁴ represents a group havingcondensed aromatic rings.

Examples of the aromatic ring group represented by Are include residuegroups derived from benzene, biphenyl, terphenyl, phenanthrene,fluoranthene, anthracene, pyrene, perylene, coronene, chrysene, picene,fluorene, carbazole, rubicene, benzoanthracene and dibenzoanthracene.

Examples of the arylene group represented by A⁹ to A¹¹ include divalentresidue groups derived from the aromatic compounds described above asthe examples of the aromatic ring group represented by Art.

Examples of the alkyl group having 1 to 6 carbon atoms represented byA¹² to A¹⁴ include methyl group, ethyl group, propyl group, isopropylgroup, butyl group, isobutyl group, sec-butyl group, tert-butyl group,various types of pentyl group and various types of hexyl group.

Examples of the cycloalkyl group having 3 to 6 carbon atoms representedby A¹² to A¹⁴ include cyclopropyl group, cyclobutyl group, cyclopentylgroup and cyclohexyl group.

Examples of the alkoxyl group having 1 to 6 carbon atoms represented byA¹² to A¹⁴ include methoxyl group, ethoxyl group, propoxyl group,isopropoxyl group, butoxyl group, isobutoxyl group, sec-butoxyl group,tert-butoxyl group, various types of pentyloxyl groups and various typesof hexyloxyl groups.

Examples of the aryloxyl group having 5 to 18 carbon atoms representedby A¹² to A¹⁴ include phenoxyl group, tolyloxyl group and naphthyloxylgroup.

Examples of the aralkyloxyl group having 7 to 18 carbon atomsrepresented by A¹² to A¹⁴ include benzyloxyl group, phenetyloxyl groupand naphthylmethoxyl group.

Examples of the arylamino group having 5 to 16 carbon atoms representedby A¹² to A¹⁴ include diphenylamino group, ditolylamino group,dinaphthylamino group and naphthylphenylamino group.

Examples of the ester group having 1 to 6 carbon atoms represented byA¹² to A¹⁴ include methoxycarbonyl group, ethoxycarbonyl group,propoxycarbonyl group and isopropoxycarbonyl group.

Examples of the halogen atoms represented by A¹² to A¹⁴ include fluorineatom, chlorine atom and bromine atom. The aryl group in the presentinvention includes styrylphenyl group, styrylbiphenyl group andstyrylnaphthyl group.

As the compound having condensed rings represented by general formula(IV), compounds having condensed rings represented by the followinggeneral formula (IV-a):

wherein A⁹ to A¹⁴ are as defined above, R²¹ to R²³ each independentlyrepresent hydrogen atom, an alkyl group having 1 to 6 carbon atoms, acycloalkyl group having 3 to 6 carbon atoms, an alkoxyl group having 1to 6 carbon atoms, an aryloxyl group having 5 to 18 carbon atoms, anaralkyloxyl group having 7 to 18 carbon atoms, an arylamino group having5 to 16 carbon atoms, nitro group, cyano group, an ester group having 1to 6 carbon atoms or a halogen atom, and at least one of A⁹ to A¹⁴represents a group having condensed aromatic rings having at least 3rings, are preferable.

Examples of the groups represented by R²¹ to R²³ include the groupsdescribed as the examples of the groups represented by A¹² to A¹⁴ ingeneral formula (IV).

Examples of the substituent in the compounds represented by the abovegeneral formulae (I) to (IV), (I-a), (I-b), (II-a), (III-a) and (IV-a)include alkyl groups having 1 to 6 carbon atoms, cycloalkyl groupshaving 3 to 6 carbon atoms, alkoxyl groups having 1 to 6 carbon atoms,aryloxyl groups having 5 to 18 carbon atoms, aralkyloxyl groups having 7to 18 carbon atoms, arylamino groups having 5 to 16 carbon atoms, nitrogroup, cyano group, ester groups having 1 to 6 carbon atoms and halogenatoms. Specific examples of the above substituent include thesubstituents described as the examples of the substituents for thegroups represented by A¹² to A¹⁴ in the above general formula (IV).

[5] Metal Complex Compounds

Examples of the metal complex compound described above include8-hydroxyquinolinatolithium, bis(8-hydroxyquinolinato)zinc,bis(8-hydroxyquinolinato)copper, bis(8-hydroxyquinolinato)manganese,tris(8-hydroxyquinolinato)aluminum,tris(2-methyl-8-hydroxyquinolinato)-aluminum,tris(8-hydroxyquinolinato)gallium,bis(10-hydroxybenzo[h]-quinolinato)beryllium,bis(10-hydroxybenzo[h]quinolinato)zinc,bis(2-methyl-8-hydroxyquinolinato)chlorogallium,bis(2-methyl-8-hydroxy-quinolinato)(o-cresolato)gallium,bis(2-methyl-8-hydroxyquinolinato)-(1-naphtholato)aluminum andbis(2-methyl-8-hydroxyquinolinato)-(2-naphtholate)gallium. Among thesecompounds, aluminum chelate complex compounds such astris(8-hydroxyquinolinato)aluminum,tris(2-methyl-8-hydroxyquinolinato)aluminum andbis(2-methyl-8-hydroxyquinolinato)(1-naphtholato)aluminum arepreferable.

In the present invention, the anthracene derivative of component (B) maybe used singly or in combination of two or more.

Specific examples of the anthracene derivative represented by the abovegeneral formula (I-a) are shown in the following.

(Me: methyl group; similarly in the following formulae)

Specific examples of the anthracene derivative represented by the abovegeneral formula (I-b) are shown in the following.

Specific examples of the anthracene derivatives represented by the abovegeneral formula (II-a) are shown in the following.

Specific examples of the spirofluorene derivative represented by theabove general formula (III-a) are shown in the following.

Specific examples of the compound having condensed rings represented bythe above general formula (IV-a) are shown in the following.

Specific examples of the arylamine compounds represented by the abovegeneral formulae (V), (V-a) and (V-b) are shown in the following.

In the present invention, the ratio of the amount by weight of thearylamine of component (A) to the amount by weight of the anthracenederivative of component (B) in the layer of an organic light emittingmedium is in the range of 1:99 to 99:1. It is preferable that the ratioof the amounts is suitably selected in accordance with the type of thecompounds used. It is more preferable that, taking it into considerationthat the compound of component (A) has the hole transporting propertyand the compound of component (B) has the electron transportationproperty, the ratio of the amounts is selected in a manner such that thelife and the efficiency of the obtained device are maximized.

It is preferable that the ratio of the amount by weight of component (A)to the amount by weight of component (B) is in the range of 1:99 to20:80. A particularly high efficiency can be obtained in this range.

It is preferable that the layer of an organic light emitting medium hasa thickness in the range of 5 to 200 nm and more preferably in the rangeof 10 to 40 nm since the voltage applied to the device can be lowered toa great extent.

Due to the use of component (A) in combination with component (A) forthe layer of an organic light emitting medium, the efficiency can beincreased by 3 to 5 times as much as the efficiency obtained by usingcomponent (A) alone and the life can be increased by at least 3 times,and by at least 10 times when optimized, as long as the life obtained byusing component (A) alone.

Due to the use of the arylamine represented by general formula (V) ascomponent (A), the concentration quenching due to an increase in theassociation of molecules can be prevented since the steric hindranceincreases and the life can be further increased. When a branched alkylgroup is introduced into the substituent of amino group or the condensedaromatic ring, the half width of the spectrum of the emitted light whichcan be used as the index for the purity of color is decreased since thesteric repulsion between the condensed aromatic ring and the substituentof amino group is increased and the spectrum of the emitted lightbecomes sharp. Therefore, the obtained device is suitable for full colordisplays.

Due to the use of component (A) and component (B) in combination, thestability and the heat resistance are improved since the layer of anorganic light emitting layer becomes more amorphous. It is preferablethat the compound of component (B) has a glass transition temperature of110° C. or higher. It is also preferable that the compound of component(A) has a glass transition temperature of 70° C. or higher. By mixingthe compounds having the above glass transition temperatures, the glasstransition temperature of the layer of an organic light emitting mediumcan be made 90° C. or higher and a durability in storage of 500 hours orlonger at 85° C. can be achieved.

The organic EL device of the present invention comprises the layer of anorganic light emitting medium (referred to as the light emitting mediumlayer, hereinafter) which comprises the combination of component (A) andcomponent (B) and is disposed between a pair of electrodes. In theorganic EL device of the present invention, it is preferable thatvarious intermediate layers are disposed between the electrodes and thelight emitting medium layer. Examples of the intermediate layer includea hole injecting layer, a hole transporting layer, an electron injectinglayer and an electron transporting layer. It is known that variousorganic and inorganic compounds can be used for these layers.

Typical examples of the construction of the organic EL device include:

(1) An anode/a light emitting layer/a cathode;

(2) An anode/a hole injecting layer/a light emitting layer/a cathode;

(3) An anode/a light emitting layer/an electron injecting layer/acathode;

(4) An anode/a hole injecting layer/a light emitting layer/an electroninjecting layer/a cathode;

(5) An anode/an organic semiconductor layer/a light emitting layer/acathode;

(6) An anode/an organic semiconductor layer/an electron barrier layer/alight emitting layer/a cathode;

(7) An anode/an organic semiconductor layer/a light emitting layer/anadhesion improving layer/a cathode;

(8) An anode/a hole injecting layer/a hole transporting layer/a lightemitting layer/an electron injecting layer/a cathode;

(9) An anode/an insulating layer/a light emitting layer/an insulatinglayer/a cathode;

(10) An anode/an inorganic semiconductor layer/an insulating layer/alight emitting layer/an insulating layer/a cathode;

(11) An anode/an organic semiconductor layer/an insulating layer/a lightemitting layer/an insulating layer/a cathode;

(12) An anode/an insulating layer/a hole injecting layer/a holetransporting layer/a light emitting layer/an insulating layer/a cathode;and

(13) An anode/an insulating layer/a hole injecting layer/a holetransporting layer/a light emitting layer/an electron injecting layer/acathode.

Among the above constructions, construction (8) is preferable. However,the construction of the organic EL device is not limited to the aboveexamples.

In general, the organic EL device is prepared on a substrate whichtransmits light. The substrate which transmits light is the substratewhich supports the organic EL device. It is preferable that thesubstrate which transmits light has a transmittance of light of 50% orgreater in the visible region of 400 to 700 nm. It is also preferablethat a flat and smooth substrate is used.

As the substrate which transmits light, for example, glass plates andsynthetic resin plates are advantageously used. Specific examples of theglass plate include plates made of soda ash glass, glass containingbarium and strontium, lead glass, aluminosilicate glass, borosilicateglass, barium borosilicate glass and quartz. Specific examples of thesynthetic resin plates include plates made of polycarbonate resins,acrylic resins, polyethylene terephthalate resins, polyether sulfideresins and polysulfone resins.

As the anode, an electrode made of a material such as a metal, an alloy,a conductive compound and a mixture of these materials which has a greatwork function (4 eV or more) is preferably used. Specific examples ofthe material for the anode include metals such as Au and conductivematerials such as CuI, ITO (indium tin oxide), SnO₂, ZnO and In—Zn—O.The anode can be prepared by forming a thin film of the electrodematerial described above in accordance with a process such as the vapordeposition process and the sputtering process. When the light emittedfrom the light emitting layer is obtained through the anode, it ispreferable that the anode has a transmittance of the emitted lightgreater than 10%. It is also preferable that the sheet resistivity ofthe anode is several hundred Ω/□ or smaller. The thickness of the anodeis, in general, selected in the range of 10 nm to 1 μm and preferably inthe range of 10 to 200 nm although the preferable range may be differentdepending on the used material.

As the cathode, an electrode made of a material such as a metal, analloy, a conductive compound and a mixture of these materials which hasa small work function (4 eV or smaller) is used. Specific examples ofthe material for the cathode include sodium, sodium-potassium alloys,magnesium, lithium, magnesium-silver alloys, aluminum/aluminum oxide,Al/Li₂O, Al/LiO₂, Al/LiF, aluminum-lithium alloys, indium and rare earthmetals.

The cathode can be prepared by forming a thin film of the electrodematerial described above in accordance with a process such as the vapordeposition process and the sputtering process.

When the light emitted from the light emitting medium layer is obtainedthrough the cathode, it is preferable that the cathode has atransmittance of the emitted light greater than 10%. It is alsopreferable that the sheet resistivity of the cathode is several hundredΩ/□ or smaller. The thickness of the cathode is, in general, selected inthe range of 10 nm to 1 μm and preferably in the range of 50 to 200 nmalthough the preferable range may be different depending on the materialused.

In the organic EL device of the present invention, it is preferable thata layer of a chalcogenide, a metal halide or a metal oxide (this layermay occasionally be referred to as a surface layer) is disposed on thesurface of at least one of the pair of electrodes prepared as describedabove. Specifically, it is preferable that a layer of a chalcogenide(including an oxide) of a metal such as silicon and aluminum is disposedon the surface of the anode at the side of the light emitting mediumlayer and a layer of a metal halide or a metal oxide is disposed on thesurface of the cathode at the side of the light emitting medium layer.Due to the above layers, stability in driving can be improved.

Preferable examples of the chalcogenide include SiO_(x) (1□x□2), AlO_(x)(1□x□1.5), SiON and SiAlON. Preferable examples of the metal halideinclude LiF, MgF₂, CaF₂ and fluorides of rare earth metals. Preferableexamples of the metal oxide include Cs₂O, Li₂O, MgO, SrO, BaO and CaO.

In the organic EL device of the present invention, the electrontransporting property and the hole transporting property of the lightemitting medium layer are simultaneously improved by suitably adjustingthe relative amounts of component (A) and component (B) described aboveand the above intermediate layers such as the hole injecting layer, thehole transporting layer and the electron injecting layer can be omitted.In this case, it is preferable that the surface layer described above isdisposed.

In the organic EL device of the present invention, it is preferable thata mixed region of an electron transfer compound and a reducing dopant ora mixed region of a hole transfer compound and an oxidizing dopant isdisposed on the surface of at least one of the pair of electrodesprepared as described above. Due to the mixed region disposed asdescribed above, the electron transfer compound is reduced to form ananion and injection and transportation of electrons from the mixedregion into the light emitting medium can be facilitated. The holetransfer compound is oxidized to form a cation and injection andtransportation of holes from the mixed region into the light emittingmedium is facilitated. Preferable examples of the oxidizing dopantinclude various types of Lewis acid and acceptor compounds. Preferableexamples of the reducing dopant include alkali metals, compounds ofalkali metals, alkaline earth metals, rare earth metals and compounds ofthese metals.

In the organic EL device of the present invention, the light emittingmedium layer has the following functions:

(1) The injecting function: the function of injecting holes from theanode or the hole injecting layer and injecting electrons from thecathode or the electron injecting layer when an electric field isapplied;

(2) The transporting function: the function of transporting injectedcharges (electrons and holes) by the force of the electric field; and

(3) The light emitting function: the function of providing the field forrecombination of electrons and holes and leading the recombination tothe emission of light.

As the process for forming the light emitting medium layer, aconventional process such as the vapor deposition process, the spincoating process and the Langmuir-Blodgett process (the LB process) canbe used. It is particularly preferable that the organic light emittingmedium layer is a molecular deposit film. The molecular deposit film isa thin film formed by deposition of a material compound in the gas phaseor a thin film formed by solidification of a material compound in asolution or in the liquid phase. In general, the molecular deposit filmcan be distinguished from the thin film formed in accordance with the LBprocess (the molecular accumulation film) based on the differences inthe aggregation structure and higher order structures and functionaldifferences caused by these structural differences.

As disclosed in Japanese Patent Application Laid-Open No. Showa 57(1982)-51781, the light emitting medium layer can also be formed bydissolving a binder such as a resin and the material compounds into asolvent to prepare a solution, followed by forming a thin film from theprepared solution in accordance with the spin coating process or thelike.

In the present invention, where desired, the light emitting medium layermay comprise conventional organic light emitting media other thancomponent (A) and component (B) described above or the light emittingmedium layer comprising the compounds described in the present inventionmay be laminated with a light emitting medium layer comprising otherconventional organic light emitting media as long as the object of thepresent invention is not adversely affected.

The hole injecting layer and the hole transporting layer are layerswhich help injection of holes into the light emitting medium layer andtransport the holes to the light emitting region. The layers exhibit agreat mobility of holes and, in general, have an ionization energy assmall as 5.5 eV or smaller. For the hole injecting layer and the holetransporting layer, a material which transports holes to the lightemitting medium layer at a small electric field strength is preferable.A material which exhibits, for example, a mobility of holes of at least10⁻⁶ cm²/V·sec under application of an electric field of 10⁴ to 10⁶ V/cmis more preferable. A material can be selected from materials which areconventionally used as the charge transporting material of holes inphotoconductive materials and conventional materials which are used forthe hole injecting layer in organic EL devices.

To form the hole injecting layer or the hole transporting layer, a thinfilm may be formed from a material for the hole injecting layer or thehole transporting layer, respectively, in accordance with a conventionalprocess such as the vacuum vapor deposition process, the spin coatingprocess, the casting process and the LB process. The thickness of thehole injecting layer and the hole transporting layer is not particularlylimited. In general, the thickness is 5 nm to 5 μm.

The electron injection layer is a layer which helps injection ofelectrons into the light emitting medium layer and exhibits a greatmobility of electrons. The adhesion improving layer is a layer made of amaterial exhibiting excellent adhesion with the cathode among theelectron injecting layer. As the material for the electron injectinglayer, metal complexes of 8-hydroxyquinoline and derivatives thereof arepreferably used. Specific examples of the metal complex of8-hydroxyquinoline and derivatives thereof include metal chelates ofoxinoid compounds including chelates of oxine (in general, 8-quinolinolor 8-hydroxyquinoline). For example, tris(8-quinolinol)aluminum can beused as the electron injecting material.

The organic EL device of the present invention tends to form defects inpixels due to leak and short circuit since an electric field is appliedto ultra-thin films. To prevent the formation of the defects, a layer ofan insulating thin film may be inserted between the pair of electrodes.

Examples of the material used for the insulating layer include aluminumoxide, lithium fluoride, lithium oxide, cesium fluoride, cesium oxide,magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride,aluminum nitride, titanium oxide, silicon oxide, germanium oxide,silicon nitride, boron nitride, molybdenum oxide, ruthenium oxide andvanadium oxide. Mixtures and laminates of the above compounds can alsobe used.

To prepare the organic EL device of the present invention, for example,the anode, the light emitting medium layer and, where necessary, thehole injecting layer and the electron injecting layer are formed inaccordance with the above process using the above materials and thecathode is formed in the last step. The organic EL device may beprepared by forming the above layers in the order reverse to thatdescribed above, i.e., the cathode being formed in the first step andthe anode in the last step.

An embodiment of the process for preparing an organic EL device having aconstruction in which an anode, a hole injecting layer, a light emittingmedium layer, an electron injecting layer and a cathode are disposedsuccessively on a substrate which transmits light will be described inthe following.

On a suitable substrate which transmits light, a thin film made of amaterial for the anode is formed in accordance with the vapor depositionprocess or the sputtering process so that the thickness of the formedthin film is 1 μm or smaller and preferably in the range of 10 to 200nm. The formed thin film is used as the anode. Then, a hole injectinglayer is formed on the anode. The hole injecting layer can be formed inaccordance with the vacuum vapor deposition process, the spin coatingprocess, the casting process or the LB process, as described above. Thevacuum vapor deposition process is preferable because a uniform film canbe easily obtained and the possibility of formation of pin holes issmall. When the hole injecting layer is formed in accordance with thevacuum vapor deposition process, in general, it is preferable that theconditions are suitably selected in the following ranges: thetemperature of the source of the deposition: 50 to 450° C.; the vacuum:10⁻⁷ to 10⁻³ Torr; the rate of deposition: 0.01 to 50 nm/second; thetemperature of the substrate: −50 to 300° C. and the thickness of thefilm: 5 nm to 5 μm; although the conditions of the vacuum vapordeposition are different depending on the used compound (the materialfor the hole injecting layer) and the crystal structure and therecombination structure of the hole injecting layer to be formed.

Then, the light emitting medium layer is formed on the hole injectinglayer formed above. Using the organic light emitting medium described inthe present invention, a thin film of the organic light emitting mediumcan be formed in accordance with the vacuum vapor deposition process,the sputtering process, the spin coating process or the casting processand the formed thin film is used as the light emitting medium layer. Thevacuum vapor deposition process is preferable because a uniform film canbe easily obtained and the possibility of formation of pin holes issmall. When the light emitting medium layer is formed in accordance withthe vacuum vapor deposition process, in general, the conditions of thevacuum vapor deposition process can be selected in the same ranges asthose described for the vacuum vapor deposition of the hole injectinglayer although the conditions are different depending on the usedcompound. It is preferable that the thickness is in the range of 10 to40 nm.

An electron injecting layer is formed on the light emitting medium layerformed above. Similarly to the hole injecting layer and the lightemitting medium layer, it is preferable that the electron injectinglayer is formed in accordance with the vacuum vapor deposition processsince a uniform film must be obtained. The conditions of the vacuumvapor deposition can be selected in the same ranges as those describedfor the vacuum vapor deposition of the hole injecting layer and thelight emitting medium layer.

A cathode is formed on the electron injecting layer formed above in thelast step and an organic EL device can be obtained. The cathode is madeof a metal and can be formed in accordance with the vacuum vapordeposition process or the sputtering process. It is preferable that thevacuum vapor deposition process is used in order to prevent formation ofdamages on the lower organic layers during the formation of the film.

In the above preparation of the organic EL device, it is preferable thatthe above layers from the anode to the cathode are formed successivelywhile the preparation system is kept in a vacuum after being evacuated.

The organic EL device which can be prepared as described above emitslight when a direct voltage of 3 to 40 V is applied in the conditionthat the anode is connected to a positive electrode (+) and the cathodeis connected to a negative electrode (−). When the connection isreversed, no electric current is observed and no light is emitted atall. When an alternating voltage is applied to the organic EL device,light emission is observed only in the condition that the polarity ofthe anode is positive and the polarity of the cathode is negative. Whenan alternating voltage is applied to the organic EL device, any type ofwave shape can be used.

The present invention also provides the organic light emitting mediumcomprising component (A) and component (B) described above. The organiclight emitting medium is advantageously used for the organicelectroluminescence device having excellent heat resistance and a longlife and efficiently emitting bluish to yellowish light.

The present invention will be described more specifically with referenceto examples in the following. However, the present invention is notlimited to the examples.

Example 1

On a glass plate having a size of 25×75×1.1 mm, a transparent electrodemade of indium tin oxide and having a thickness of 120 nm was formed.After the glass substrate was cleaned by irradiation with ultravioletlight and exposure to ozone, the glass substrate was placed in a vacuumvapor deposition apparatus.

AfterN,N′-bis[4-(diphenylamino)phenyl]-N,N′-diphenylbiphenyl-4,4′-diamine wasvapor deposited so that a hole injecting layer having a thickness of 60nm was formed, N,N,N′,N′-tetrakis(4-biphenyl)-4,4′-benzidine was vapordeposited on the formed hole injecting layer so that a hole transportinglayer having a thickness of 20 nm was formed. Then, compound (EM4) shownabove as component (B) and compound (EM83) shown above as component (A)were simultaneously vapor deposited in amounts such that the ratio ofthe amount by weight of component (B) to the amount by weight ofcomponent (A) was 40:3 so that a light emitting layer having a thicknessof 40 nm was formed.

On the formed light emitting layer, tris(8-hydroxyquinolinato)-aluminum(Alq) was vapor deposited so that an electron injecting layer having athickness of 20 nm was formed. Lithium fluoride (LiF) was vapordeposited so that a layer having a thickness of 0.3 nm was formed andthen aluminum (Al) was vapor deposited so that a layer having athickness of 150 nm was formed. The formed LiF/Al film worked as thecathode. An organic EL device was prepared as described above.

The prepared organic EL device was tested by passing an electriccurrent. Light emission of pure blue color (the half width: 42 nm)having a luminance of 205 cd/m² was obtained at a voltage of 6.5 V and acurrent density of 10 mA/cm². The device was tested by continuouslypassing a direct current at an initial luminance of 500 cd/m² and thehalf-life time was found to be 900 hours.

Examples 2 to 19

Organic EL devices were prepared in accordance with the same proceduresas those conducted in Example 1 except that compounds shown in Table 1were used as component (B) and component (A). The results of testing theobtained devices by passing an electric current at a current density of10 mA/cm² are shown in Table 1. The half-life times obtained by the testof continuous passage of a direct current at initial luminances shown inTable 1 are also shown in Table 1.

Comparative Example 1

An organic EL device was prepared in accordance with the same proceduresas those conducted in Example 1 except that a light emitting layerhaving a thickness of 40 nm was formed with compound (EM4) alone inplace of the combination of compound (EM4) and compound (EM83) used inExample 1. The results of testing the obtained device by passing anelectric current at a current density of 10 mA/cm² are shown in Table 1.The device was tested by continuously passing a direct current at aninitial luminance of 500 cd/m² and the half-life time was found to be asshort as 90 hours.

Comparative Example 2

An organic EL device was prepared in accordance with the same proceduresas those conducted in Example 1 except that4,4′-bis(diphenylamino)stilbene (H2) was used in place of compound(EM83) used in Example 1. The results of testing the obtained device bypassing an electric current at a current density of 10 mA/cm² are shownin Table 1. The device was tested by continuously passing a directcurrent at an initial luminance of 500 cd/m² and the half-life time wasfound to be as short as 300 hours.

Comparative Example 3

An organic EL device was prepared in accordance with the same proceduresas those conducted in Example 1 except that2,5,8,11-tetra-t-butylperylene (H3) was used in place of compound (EM83)used in Example 1. The results of testing the obtained device by passingan electric current at a current density of 10 mA/cm² are shown inTable 1. The device was tested by continuously passing a direct currentat an initial luminance of 1,000 cd/m² and the half-life time was foundto be as short as 200 hours.

Comparative Example 4

An organic EL device was prepared in accordance with the same proceduresas those conducted in Example 1 except thatN,N′-di(naphthalen-2-yl),N,N′-diphenylbenzene (H4) was used in place ofcompound (EM83) used in Example 1. The results of testing the obtaineddevice by passing an electric current at a current density of 10 mA/cm²are shown in Table 1. The device was tested by continuously passing adirect current at an initial luminance of 500 cd/m² and the half-lifetime was found to be as short as 200 hours.

Comparative Example 5

An organic EL device was prepared in accordance with the same proceduresas those conducted in Example 11 except that1,3-bis-[2-{4-N,N′-(diphenylamino)phenyl}vinyl]benzene (H5) was used inplace of compound (EM98) used in Example 11. The results of testing theobtained device by passing an electric current at a current density of10 mA/cm² are shown in Table 1. The device was tested by continuouslypassing a direct current at an initial luminance of 1,000 cd/m² and thehalf-life time was found to be as short as 750 hours.

Example 20

An organic EL device was prepared in accordance with the same proceduresas those conducted in Example 1 except that compounds shown in Table 2were used as component (B) and component (A) and Alq:Cs/Al was used asthe cathode. Alq:Cs/Al was a mixed layer containing Alq and Cs (cesium)metal as the electron transporting compounds in relative amounts by moleof 1:1. The results of testing the obtained device by passing anelectric current at a current density of 10 mA/cm² are shown in Table 2.The half-life time obtained by the test of continuous passage of adirect current at the initial luminance shown in Table 2 is also shownin Table 2.

Examples 21 and 22

An organic EL device was prepared in accordance with the same proceduresas those conducted in Example 20 except that compounds shown in Table 2were used as component (B) and component (A). The results of testing theobtained devices by passing an electric current at a current density of10 mA/cm² are shown in Table 2. The half-life times obtained by the testof continuous passage of a direct current at initial luminances shown inTable 2 are also shown in Table 2.

TABLE 1 Components of light emitting layer Luminance Efficiency com- ofemitted of light ponent component Voltage light emission (B) (A) (V)(cd/m²) (cd/A) Example 1 EM4 EM83 6.5 205 2.05 Example 2 EM4 EM110 6.3310 3.10 Example 3 EM5 EM111 6.0 325 3.25 Example 4 EM5 EM77 6.8 1951.95 Example 5 EM5 EM117 6.0 295 2.95 Example 6 EM27 EM110 6.5 190 1.90Example 7 EM37 EM111 6.0 180 1.80 Example 8 EM43 EM110 6.2 165 1.65Example 9 EM49 EM111 6.3 170 1.70 Example 10 EM4 EM60 6.0 350 3.50Example 11 EM4 EM98 6.0 730 7.30 Example 12 EM5 EM60 6.0 345 3.45Example 13 EM5 EM98 6.0 815 8.15 Example 14 EM5 EM97 6.5 5 5.50 Example15 EM27 EM98 6.0 355 3.55 Example 16 EM42 EM97 6.5 395 3.95 Example 17EM46 EM98 6.0 500 5.00 Example 18 EM4 EM89 7.0 1050 10.50 Example 19 EM4EM94 7.5 950 9.50 Comparative EM4 6.3 90 0.90 Example 1 Comparative EM4H2 6.8 105 1.05 Example 2 Comparative EM4 H3 6.5 200 2.00 Example 3Comparative EM4 H4 7.0 96 0.96 Example 4 Comparative EM4 H5 6.8 510 5.10Example 5 Half-life Initial Color of Half width time luminance emittedlight (nm) (hour) (cd/m²) Example 1 pure blue 42 900 500 Example 2 pureblue 43 2900 500 Example 3 pure blue 45 3050 500 Example 4 pure blue 42680 500 Example 5 pure blue 44 1000 500 Example 6 pure blue 44 1150 500Example 7 pure blue 45 1200 500 Example 8 pure blue 43 950 500 Example 9pure blue 45 1100 500 Example 10 blue 40 800 1000 Example 11 blue 503100 1000 Example 12 blue 41 700 1000 Example 13 blue 49 3200 1000Example 14 blue 48 2950 1000 Example 15 blue 49 1500 1000 Example 16blue 49 900 1000 Example 17 blue 50 1000 1000 Example 18 green 68 10503000 Example 19 green 65 750 3000 Comparative pure blue 45 90 500Example 1 Comparative pure blue 58 300 500 Example 2 Comparative green69 200 1000 Example 3 Comparative pure blue 46 100 500 Example 4Comparative blue 62 500 1000 Example 5

TABLE 2 Components of light emitting layer Luminance Efficiency com- ofemitted of light ponent component Voltage light emission (B) (A) (V)(cd/m²) (cd/A) Example 20 EM32 EM111 5.0 290 2.90 Example 21 EM4 EM1286.5 260 2.60 Example 22 EM5 EM128 6.0 250 2.50 Example 23 EM42 EM128 6.5155 1.55 Example 24 EM5 EM131 6.7 964 9.64 Example 25 EM5 EM133 6.5 101510.15 Example 26 EM43 EM139 7.0 950 9.50 Example 27 EM5 EM139 6.5 204020.40 Example 28 EM42 EM144 6.5 1050 10.50 Example 29 EM5 EM144 6.4 210021.00 Example 30 EM32 EM144 6.0 1555 15.60 Example 31 EM32 EM160 6.51430 14.30 Example 32 EM32 EM189 6.0 980 9.80 Example 33 Alq EM139 7.01420 14.20 Example 34 EM4 EM215 6.5 340 3.40 Example 35 EM5 EM215 6.5355 3.55 Example 36 EM42 EM215 6.7 185 1.85 Example 37 EM4 EM195 6.01050 10.50 Example 38 EM4 EM197 6.4 1030 10.30 Example 39 EM5 EM202 6.51870 18.70 Example 40 EM5 EM204 6.5 1850 18.50 Example 41 EM5 EM208 6.91350 13.50 Half-life Initial Color of Half width time luminance emittedlight (nm) (hour) (cd/m²) Example 20 pure blue 44 1300 500 Example 21pure blue 43 2100 500 Example 22 pure blue 43 2350 500 Example 23 pureblue 44 1000 500 Example 24 blue 49 4000 1000 Example 25 blue 50 41001000 Example 26 green 68 900 3000 Example 27 green 67 4500 3000 Example28 green 67 1100 3000 Example 29 green 68 4750 3000 Example 30 green 681050 3000 Example 31 green 64 1800 3000 Example 32 green 65 950 3000Example 33 green 69 1500 3000 Example 34 pure blue 44 3500 500 Example35 pure blue 44 3950 500 Example 36 pure blue 43 970 500 Example 37 blue50 4050 1000 Example 38 blue 49 3950 1000 Example 39 green 68 2100 3000Example 40 green 68 1950 3000 Example 41 green 65 1500 3000

As shown in Table 1 and Table 2, the excellent efficiencies and theexcellent lives could be achieved in the devices emitting green light,blue light and pure blue light, which was hard to obtain, as shown inExamples 1 to 41. The above results were achieved since the light havingmore excellent purity of color could be emitted due to the decrease inthe half width in comparison to those of the devices of ComparativeExamples.

In particular, the devices comprising the diaminoanthracene derivativesemitting green light, the diaminopyrene derivatives emitting blue lightand the diaminochrysene derivatives emitting pure blue light ascomponent (A) exhibited more excellent efficiencies of light emissionand lives in comparison to those of any of the devices of ComparativeExamples.

Since the anthracene derivative was used as component (B) and thediaminoanthracene derivative, the diaminopyrene derivative or thediaminochrysene derivative was used as component (A), the most excellentefficiency of light emission and life could be achieved by the devicesemitting green light, blue light and pure blue light.

INDUSTRIAL APPLICABILITY

In accordance with the present invention, the organic EL device whichexhibits excellent purity of color, has excellent heat resistance and along life and efficiently emits bluish to yellowish light and an organiclight emitting medium which can be advantageously used for the organicelectroluminescence device, can be provided.

The organic EL device can be advantageously used as the light emittingdevice in various types of display apparatuses and is particularlysuitable for full color display apparatuses.

1. (canceled)
 2. An electroluminescence device comprising a pair ofelectrodes and a layer of an organic light emitting medium disposedbetween the pair of electrodes, wherein the layer of an organic lightemitting medium comprises: (A) at least one compound selected fromarylamine compounds represented by formula (V):

wherein: X³ represents a substituted or unsubstituted residue of acondensed aromatic ring selected from the group consisting ofnaphthalene, phenanthrene, fluoranthene, anthracene, pyrene, perylene,coronene, chrysene, picene, diphenylanthracene, fluorene, triphenylene,rubicene, benzoanthracene, phenylanthracene, bisanthracene,dianthracenylbenzene, and dibenzoanthracene; each of Ar⁵ and Ar⁶independently represents a substituted or unsubstituted aromatic grouphaving 6 to 40 carbon atoms; and p represents an integer of 1 to 4; and(B) at least one compound selected from anthracene derivativesrepresented by formula (I):A¹-L-A²  (I) wherein: A¹ and A² may be the same or different and each ofA¹ and A² independently represents a substituted or unsubstitutedmonophenylanthryl group or a substituted or unsubstituteddiphenylanthryl group; and L represents a single bond or a divalentbonding group.
 3. The electroluminescence device according to claim 2,wherein X³ represents a substituted or unsubstituted residue of acondensed aromatic ring selected from the group consisting ofnaphthalene, anthracene, pyrene, and chrysene.
 4. Theelectroluminescence device according to claim 2, wherein the aromaticgroup for each of Ar⁵ and Ar⁶ is selected from the group consisting of aphenyl group, a naphthyl group, an anthranyl group, a phenanthryl group,a pyrenyl group, a coronyl group, a biphenyl group, a terphenyl group, afluorenyl group, a benzothienyl group, an indolyl group, and acarbazolyl group.
 5. The electroluminescence device according to claim2, wherein the aromatic group for each of Ar⁵ and Ar⁶ is selected fromthe group consisting of a phenyl group, a naphthyl group, a pyrenylgroup, and a biphenyl group.
 6. The electroluminescence device accordingto claim 2, wherein the arylamine compound is represented by formula(V-a):

wherein X³ is as defined in formula (V); each of Ar¹⁵ to Ar¹⁸independently represents a hydrogen atom, a substituted or unsubstitutedalkyl group having 1 to 50 carbon atoms, a substituted or unsubstitutedaryl group having 5 to 50 carbon atoms, a substituted or unsubstitutedaralkyl group having 7 to 50 carbon atoms, a substituted orunsubstituted cycloalkyl group having 3 to 50 carbon atoms, asubstituted or unsubstituted alkoxyl group having 1 to 50 carbon atoms,a substituted or unsubstituted aryloxyl group having 5 to 50 carbonatoms, a substituted or unsubstituted arylamino group having 5 to 50carbon atoms, or a substituted or unsubstituted alkylamino group having1 to 20 carbon atoms; each of g, h, i and j represents an integer of 0to 5; n represents an integer of 0 to 3; when g, h, i and j eachrepresent an integer of 2 or greater, atoms and groups represented by aplurality of Ar¹⁵ to Ar¹⁸ may be the same or different and may be bondedto each other to form a saturated or unsaturated ring; and at least oneof Ar¹⁵ to Ar¹⁸ represents a substituted or unsubstituted secondary ortertiary alkyl group having 3 to 10 carbon atoms.
 7. Theelectroluminescence device according to claim 2, wherein the arylaminecompound is represented by formula (V-a):

wherein: X³ is as defined in formula (V); each of Ar¹⁵ to Ar¹⁸independently represents a hydrogen atom, a substituted or unsubstitutedalkyl group having 1 to 50 carbon atoms, a substituted or unsubstitutedaryl group having 5 to 50 carbon atoms, a substituted or unsubstitutedaralkyl group having 7 to 50 carbon atoms, a substituted orunsubstituted cycloalkyl group having 3 to 50 carbon atoms, asubstituted or unsubstituted alkoxyl group having 1 to 50 carbon atoms,a substituted or unsubstituted aryloxyl group having 5 to 50 carbonatoms, a substituted or unsubstituted arylamino group having 5 to 50carbon atoms, or a substituted or unsubstituted alkylamino group having1 to 20 carbon atoms; each of g, h, i and j represents an integer of 0to 5; when g, h, i and j each represent an integer of 2 or greater,atoms and groups represented by a plurality of Ar¹⁵ to Ar¹⁸ may be thesame or different and may be bonded to each other to form a saturated orunsaturated ring; each of R²⁴ and R²⁵ independently represents ahydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10carbon atoms, a substituted or unsubstituted aryl group having 6 to 20carbon atoms, a substituted or unsubstituted aralkyl group having 7 to50 carbon atoms, a substituted or unsubstituted alkoxyl group having 1to 50 carbon atoms, or a substituted or unsubstituted aryloxyl grouphaving 5 to 50 carbon atoms; each of k and m represents an integer of 0to 2; and at least one of R²⁴ and R²⁵ represents a substituted orunsubstituted secondary or tertiary alkyl group having 3 to 10 carbonatoms.
 8. The electroluminescence device according to claim 2, whereinthe anthracene derivative is represented by formula (I-a):

wherein: each of R¹ to R¹⁰ independently represents a hydrogen atom, analkyl group, a cycloalkyl group, an aryl group which may be substituted,an alkoxyl group, an aryloxyl group, an alkylamino group, an alkenylgroup, an arylamino group, or a heterocyclic group which may besubstituted; each of a and b represents an integer of 1 to 5 when a andb each represent an integer of 2 or greater, atoms or groups representedby a plurality of R¹ and R² may be the same or different and may bebonded to each other to form a ring; groups represented by combinationsof R³ and R⁴, R⁵ and R⁶, R⁷ and R⁸, and R⁹ and R¹⁰ may be bonded to eachother to form a ring; and L¹ represents a single bond, —O—, —S—, —N(R)—wherein R represents an alkyl group or an aryl group which may besubstituted, an alkylene group or an arylene group.
 9. Theelectroluminescence device according to claim 2, wherein the anthracenederivative is represented by formula (I-b):

wherein: each of R¹¹ to R²⁰ independently represents a hydrogen atom, analkyl group, a cycloalkyl group, an aryl group which may be substituted,an alkoxyl group, an aryloxyl group, an alkylamino group, an arylaminogroup or a heterocyclic group which may be substituted; each of c, d, eand f represents an integer of 1 to 5; when each of c, d, e and frepresents an integer of 2 or greater, atoms or groups represented by aplurality of R¹¹, R¹², R¹⁶ and R¹⁷ may be the same or different and maybe bonded to each other to form a ring groups represented bycombinations of R¹³ and R¹⁴, and R¹⁸ and R¹⁹ may be bonded to each otherto form a ring; and L² represents a single bond, —O—, —S—, —N(R)—wherein R represents an alkyl group or an aryl group which may besubstituted, an alkylene group or an arylene group.
 10. Theelectroluminescence device according to claim 2, wherein a weight ratioof the component (A) and the component (B) is 1:99 to 20:80.
 11. Theelectroluminescence device according to claim 2, wherein a layer of achalcogenide, a layer of a metal halide or a layer of a metal oxide isdisposed at least on one surface of the pair of electrodes.
 12. Theelectroluminescence device according to claim 2, wherein a mixed regioncomprising a reducing dopant and organic substances or a mixed regioncomprising an oxidizing dopant and organic substances is disposed atleast on one surface of the pair of electrodes.
 13. Theelectroluminescence device according to claim 2, wherein a thickness ofthe layer of an organic light emitting medium is 10 to 400 nm.
 14. Anorganic light emitting medium comprising: (A) at least one compoundselected from arylamine compounds represented by formula (V):

wherein: X³ represents a substituted or unsubstituted residue of acondensed aromatic ring selected from the group consisting ofnaphthalene, phenanthrene, fluoranthene, anthracene, pyrene, perylene,coronene, chrysene, picene, diphenylanthracene, fluorene, triphenylene,rubicene, benzoanthracene, phenylanthracene, bisanthracene,dianthracenylbenzene, and dibenzoanthracene; each of Ar⁵ and Ar⁶independently represents a substituted or unsubstituted aromatic grouphaving 6 to 40 carbon atoms; and p represents an integer of 1 to 4; and(B) at least one compound selected from anthracene derivativesrepresented by formula (I):A¹-L-A²  (I) wherein: A¹ and A² may be the same or different and each ofA¹ and A² independently represents a substituted or unsubstitutedmonophenylanthryl group or a substituted or unsubstituteddiphenylanthryl group; and L represents a single bond or a divalentbonding group.